悬索桥上部结构的抗震设计

Seismic design of suspension bridge superstructures

大跨悬索桥必须进行可靠的抗震设计。由于悬索桥第一自振周期长达几十ｓ，有多达百余个自振周期密集在０．５～５ｓ区段内，现行桥梁抗震规范不适用于大跨悬索桥。配合交通部“公路悬索桥设计规范”编制的研究工作，讨论了反应谱５ｓ以上长周期段、反应谱振型分解法的振型组合方式及应组合的振型数、以及时程积分时的地震记录的持续时间对大跨悬索桥地震反应的影响，发现它们的影响十分显著。从而对悬索桥上部结构抗震设计的某些要点提出建议。

The first natural periods of suspension bridges are longer than 10s. Most of their natural periods are closely spaced. The seismic design of suspension bridges is different from other bridges. Significant effects on suspension bridge seismic responses of the components of response spectra with periods longer than 5s, the different mode combination rules, the number of modes to be covered in mode combination, the time duration of seismic acceleration histories and the vertical components of seismic ground motions are discussed. Practrcal procedures for seismic design of suspension bridges are recommended.